1. Field of the Invention
The invention is based on a circuit arrangement of modular design, in particular for propulsion of a railroad vehicle, as claimed in the preamble of patent claim 1.
2. Discussion of Background
A circuit arrangement of the type mentioned initially is described, in particular, in FIG. 6 of DE 196 30 284 A1. This circuit arrangement comprises n partial converter modules 40.1, . . . , 40.n, which are connected in series with one another and have outputs which are connected in parallel with one another. The outputs can be connected to partial converter modules 41.1, . . . 41.m, each having a traction motor 42.1, . . . , 42.m. The partial converter modules 40.1, . . . 40.n split the relatively high AC voltage between the traction wire 36 and the rail 37 of propulsion for a railroad vehicle corresponding to the number n of converter modules. A low output voltage is produced at the outputs of the partial converter modules 40.1, . . . 40.n, reduced corresponding to the number of modules n, is, in each case DC-isolated from the input voltage by a transformer 6 (FIG. 1) and feeds the traction motors 42.1, . . . 42.m, via the partial converter modules 43.1, . . . 43.m. Conversely, when the railroad vehicle is being braked, the traction motors can also feed power into the power supply system via the partial converter module. Since only a low voltage is supplied to each of the partial converter modules, they can be operated in a cost-effective manner using semiconductor switches 11 (FIG. 1) having a normal withstand voltage.